US20150145851A1 - Display device - Google Patents

Abstract

A display device is provided with an image processing circuit that outputs a pixel value of each pixel to a pixel driving circuit, the pixel driving circuit that inputs a pixel voltage to each of pixels based on the pixel value of each of the pixels, and a control circuit that detects a defective pixel. Here, the image processing circuit corrects the pixel value of the defective pixel in the image data to be displayed which is input to the image processing circuit, to a pixel value for black, and then outputs each pixel value of the image data to be displayed in which the pixel value of the defective pixel is corrected to the pixel value for black, to the pixel driving circuit.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS
• The present application claims priority from Japanese application JP 2013-243250 filed on Nov. 25, 2013, the content of which is hereby incorporated by reference into this application.
BACKGROUND OF THE INVENTION
• 1. Field of the Invention
• The present invention is related to a display device.
• 2. Description of Related Art
• A display device has been known, which is provided with a display panel formed of a plurality of pixels, each of which includes a current drive type light emitting element and a controlling element controlling current passing through the light emitting element based on an input pixel voltage. For example, the display panel is disclosed in JP 2008-241803 A. The display device disclosed in JP 2008-241803 A is configured to derive an offset voltage to all pixels and emit light to each light emitting element based on the offset voltage with prescribed luminance.
SUMMARY OF THE INVENTION
• In the display device as described above, the display panel may include a defective pixel including the light emitting element in which an anode and a cathode are short-circuited by foreign matter. In such a defective pixel, even in a case where the light emitting element does not emit light, a large amount of current is consumed in the light emitting element.
• An object of the present invention is to cause current being consumed in a defective pixel to be suppressed in a display device which is provided with a display panel formed of a plurality of pixels including a current drive type light emitting element and controlling current passing through a light emitting element based on an input pixel voltage.
• According to an aspect of the present invention, there is provided a display device including a display panel that is formed of a plurality of pixels, each of which includes a current drive type light emitting element and controls current passing through the current drive type light emitting element based on an input pixel voltage; an image processing circuit that outputs a pixel value of each of the pixels; a pixel voltage input circuit that inputs a pixel voltage to each of the pixels based on the pixel value of each of the pixels output from the image processing circuit, and a defect detecting circuit that detects a defective pixel having a defect among the plurality of pixels, in which the image processing circuit includes a correction circuit that corrects the pixel value of the defective pixel in image data to be displayed which is input to the image processing circuit, and then outputs each pixel value of the image data to be displayed in which the pixel value of the defective pixel is corrected, to the pixel voltage input circuit, and the correction circuit corrects the pixel value of the defective pixel to a pixel value for black.
• In the aspect, the current drive type light emitting element may be an organic EL element and the defective pixel may be a pixel including the organic EL element in which an anode and a cathode are short-circuited.
• In the aspect, the correction circuit may correct a pixel value of a related pixel, of the image data to be displayed, having a prescribed positional relationship to the defective pixel based on the pixel value of the defective pixel and correct the pixel value of the defective pixel in the image data to be displayed to the pixel value for black, and then output each pixel value of the image data to be displayed in which the pixel value of the defective pixel and the related pixel are corrected, to the pixel voltage input circuit.
• In the aspect, a plurality of unit areas may be set in the display panel and the defect detecting circuit may determine, for each unit area, whether or not the unit area is a defective area including the defective pixel and then detect the defective pixel in the unit area determined as the defective area.
• In the aspect, the image processing circuit may further include an image for detecting output circuit that obtains image data, the image data including the pixel value of each of the pixels for defect detection, only each of the pixel value of some of the pixels being not a pixel value for black, and then outputs each pixel value of the obtained image data to the pixel voltage input circuit, the display device may further include a current measuring unit that measures a total amount of the current passing through the current drive type light emitting element in the pixel of which the pixel value is not the pixel value for black, the image for detecting output circuit may obtain, for each unit area, the image data for defect detection of which the pixel value only in the unit area is not the pixel value for black, and then output each pixel value of the obtained image data to the pixel voltage input circuit, and the defect detecting circuit may determine whether or not the unit area is the defective area based on the measured value obtained from the current measuring unit in a case where all pixel values of the image data for defect detection of which the pixel value only in the unit area is not the pixel value for black are output to the pixel voltage input circuit.
• In the aspect, the image for detecting output circuit may obtain, for each of the pixels in the defective area, the image data for defect detection of which the pixel value only in the pixel is not the pixel value for black, and then output each pixel value of the obtained image data to the pixel voltage input circuit, and the defect detecting circuit may determine whether or not the pixel in the defective area is the defective pixel based on the measured value obtained from the current measuring unit in a case where all pixel values of the image data for defect detection of which the pixel value only in the pixel is not the pixel value for black are output.
• In addition, the correction circuit may correct the pixel value of the related pixel based on the pixel value of the defective pixel and a value according to an elapsed time from a reference timing.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a diagram illustrating a configuration of a display device according to an embodiment of the present invention.
• FIG. 2 is a diagram illustrating an example of a configuration of a pixel.
• FIG. 3 is a diagram illustrating unit areas which are set in an organic EL panel.
• FIG. 4 is a diagram illustrating a display order of first image data for detection.
• FIG. 5 is a diagram illustrating a display order of second image data for detection.
• FIG. 6 is a diagram illustrating a line memory which is provided in a gradation correction circuit.
• FIG. 7 is a flow chart illustrating a process performed in a gradation correction circuit.
• FIG. 8 is a diagram illustrating a correction example of a pixel value.
• FIG. 9 is a diagram illustrating a correction example of a pixel value.
DETAILED DESCRIPTION OF THE INVENTION
• Hereinafter, detailed description will be given below the examples of the invention with reference to the attached drawings.
• FIG. 1 is a diagram illustrating adisplay device1 according to an embodiment of the present invention. In this embodiment, thedisplay device1 is implemented as an organic EL display and provided with anorganic EL panel2, adriver3, apixel selection circuit4, apower supply circuit5, anammeter6, or the like. Theorganic EL panel2 is a general organic EL panel and is formed of a plurality of pixels which include an organic EL element, that is, a current drive type light emitting element. As pixels, three types of an R pixel which is a red pixel, a G pixel which is a green pixel and a B pixel which is a blue pixel are provided. A power supply voltage is supplied to each of the pixels from thepower supply circuit5 so as to cause emission of the organic EL element.
• Thepixel selection circuit4 selects a pixel in theorganic EL panel2. In other words, thepixel selection circuit4 inputs a selection signal to the pixel to be selected.
• Thedriver3 is provided with animage processing unit8, apixel driving circuit9, acontrol circuit10, and amemory11. The image data to be displayed which is obtained from the outside is input to theimage processing unit8. The image data to be displayed includes a pixel value of each of the pixels. Theimage processing unit8 outputs the pixel value of each of the pixels to thepixel driving circuit9. In this embodiment, if an operating mode is a normal mode, theimage processing unit8 outputs the pixel value of each of the pixels on the basis of the image data to be displayed to thepixel driving circuit9. In addition, if the operating mode is a detection mode, theimage processing unit8 outputs the pixel value of each of the pixels on the basis of the image data theimage processing unit8 generated to thepixel driving circuit9. Description of the operating mode will be made later.
• Thepixel driving circuit9 inputs the pixel voltage to each of the pixels based on the pixel value of each of the pixels output from theimage processing unit8. The pixel voltage which is input to each of the pixels is a voltage corresponding to the pixel value of each of the pixels. Each of the pixels controls the current passing through the organic EL element based on the input pixel voltage.FIG. 2 is a diagram illustrating an example of a configuration of a pixel. A portion of the inside of a dotted line indicates one pixel. As shown inFIG. 2, the pixel includes a switch SW, a capacity C, a driving transistor TR, and anorganic EL element7. A pixel voltage, the selection signal, and the power supply voltage are input to the pixel and the switch SW is turned on when the selection signal is input to the pixel and accumulates the pixel voltage into the capacitor C. The driving transistor TR supplies the driving current to theorganic EL element7 in response to the pixel voltage accumulated in the capacitor C. A luminance of light emission of theorganic EL element7 is determined by the pixel voltage accumulated in the capacity C and the power supply voltage supplied from thepower supply circuit5. However, in a case where the pixel voltage accumulated in the capacity C is a pixel voltage corresponding to a pixel value for black indicating the minimum-gradation data, a driving current does not pass through theorganic EL element7.
• Meanwhile, the driving current passing through each of theorganic EL elements7 is input to theammeter6. A total amount of the driving current passing through each of theorganic EL elements7 is measured by means of theammeter6. The measured value of theammeter6 is input to thepower supply circuit5. Thepower supply circuit5 supplies the power supply voltage not only to each of the pixels but also to thedriver3. In the embodiment, a configuration is set such that a level or a pulse width of the power supply voltage is adjusted in response to the measured value of theammeter6, the power supply voltage being supplied to thedriver3 as measurement data indicating the measured value of theammeter6.
• The measurement data or the image data to be displayed is input to thecontrol circuit10. Thecontrol circuit10 supplies a signal indicating a current operating mode or a signal indicating which pixel of the pixel value should be output to thepixel driving circuit9 to theimage processing unit8. In addition, thecontrol circuit10 supplies a signal indicating which pixel should be input to which pixel voltage to thepixel driving circuit9. Further, thecontrol circuit10 supplies a signal indicating to which pixel and at which timing the selection signal should be input to thepixel selection circuit4.
• In a case where the operating mode is the detection mode, thecontrol circuit10 detects the defective pixel in theorganic EL panel2. Here, the defective pixel means a pixel including anorganic EL element7 in which the anode and the cathode are short-circuited due to foreign matter. In the defective pixel, the driving current passing through theorganic EL element7 becomes higher due to the short-circuit. However, the driving current does not pass through a light emitting layer any more, which results in theorganic EL element7 not emitting. To briefly explain a detection method for a defective pixel, thecontrol circuit10 narrows down the defective area including the defective pixel in theorganic EL panel2 and detects the defective pixel from the narrowed down defective area.
• Specifically, as shown inFIG. 3, nine unit areas of unit area A to unit area I are set in theorganic EL panel2. When an image fordetection generation circuit12 is provided in theimage processing unit8 and the operating mode is a detection mode, nine items of first image data for detection of first image data for detection A to first image data for detection I are generated in order. The first image data for detection includes the pixel value each of the pixels and the image fordetection generation circuit12 causes each of these items of first image data for detection to be displayed on theorganic EL panel2 in order. That is, the pixel value of each of the pixels is output to thepixel driving circuit9 from the first image data for detection A in order.
• Here, the first image data for detection A is the image data in which the pixel value of a pixel outside the unit area A is the pixel value for black and the pixel value of a pixel inside the unit area A is a reference value other than the pixel value for black, and the first image data for detection B is the image data in which the pixel value of a pixel outside the unit area B is the pixel value for black and the pixel value of a pixel inside the unit area B is the aforementioned reference value. In addition, the first image data for detection C is the image data in which the pixel value of a pixel outside the unit area C is the pixel value for black and the pixel value of a pixel inside the unit area C is the aforementioned reference value, and the first image data for detection D is the image data in which the pixel value of a pixel outside the unit area D is the pixel value for black and the pixel value of a pixel inside the unit area D is the aforementioned reference value. Further, the first image data for detection E is the image data in which the pixel value of a pixel outside the unit area E is the pixel value for black and the pixel value of a pixel inside the unit area E is the aforementioned reference value, the first image data for detection F is the image data in which the pixel value of a pixel outside the unit area F is the pixel value for black and the pixel value of a pixel inside the unit area F is the aforementioned reference value, and the first image data for detection G is the image data in which the pixel value of a pixel outside the unit area G is the pixel value for black and the pixel value of a pixel inside the unit area G is the aforementioned reference value. In addition, the first image data for detection H is the image data in which the pixel value of a pixel outside the unit area H is the pixel value for black and the pixel value of a pixel inside the unit area H is the aforementioned reference value, and the first image data for detection I is the image data in which the pixel value of a pixel outside the unit area I is the pixel value for black and the pixel value of a pixel inside the unit area I is the aforementioned reference value.FIG. 4 is a diagram illustrating a display order of the first image data for detection. Arrows indicate the display order.
• In the pixel in which the pixel voltage corresponding to the pixel value for black is input, the fact that the driving current does not pass through theorganic EL element7 is described above. For that reason, for example, the measured value obtained by theammeter6 during the display of the first image data for detection A becomes a total amount of the driving current passing through theorganic EL elements7 inside the unit area A. Every time the first image data for detection is displayed, thecontrol circuit10 determines whether or not the measured value indicated by the measurement data is equal to or greater than a predetermined first threshold value. Thecontrol circuit10 determines, for each unit area, whether or not the unit area is the defective area including the defective pixel. For example, the description “determining whether or not the measured value is equal to or greater than the first threshold value when the first image data for detection A is displayed” means determining whether or not the unit area A is the defective area.
• In this manner, thecontrol circuit10 narrows down the unit area which may be the defective area.
• Next, thecontrol circuit10 detects the defective pixel from the unit area which is determined as the defective area. In other words, thecontrol circuit10 generates, for each pixel in the unit area determined as the defective area, second image data for detection which is the image data of which the pixel value of pixels is the above described reference value and the pixel value of other pixels is the pixel value for black. Further, each of these items of generated second image data for detection is caused to be displayed on theorganic EL panel2 in order. That is, the pixel value of each of the pixels is output to thepixel driving circuit9 from the second image data for detection which is the first in display order.FIG. 5 is a diagram illustrating a display order of the second image data for detection in a case where the unit area A is the defective area. Arrows indicate the display order.
• The fact that the driving current does not pass through theorganic EL elements7 in the pixels in which the pixel voltage corresponding to the pixel value for black is input is described above. For that reason, for example, the measured value obtained by theammeter6 when the second image data for detection which is the first in display order is displayed becomes the driving current passing through theorganic EL element7 of the pixel of the upper left vertex in the unit area A (refer toFIG. 5). Accordingly, in a case where the measured value is relatively high, it is considered that the pixel of the upper left vertex in the unit area is the defective pixel. Therefore, every time the second image data for detection is displayed, thecontrol circuit10 determines whether or not the measured value indicated by the measurement data is equal to or greater than a predetermined second threshold value. In this manner, thecontrol circuit10 determines, for each pixel in the unit areas determined as the defective area, whether or not a pixel is the defective pixel. In addition, thecontrol circuit10 records an address of the pixel determined as the defective pixel in thememory11. For example, the description “determining whether or not the measured value is equal to or greater than the second threshold value when the second image data for detection which is the first in display order is displayed” means determining whether or not the pixel of the upper left vertex in the unit area is the defective pixel.
• In this manner, thecontrol circuit10 detects the defective pixel and stores the address of the defective pixel in thememory11.
• In this way, in thedisplay device1, the unit areas including the defective pixel are narrowed down first and then the defective pixel is detected from the unit area including the defective pixel. Therefore, without narrowing down the unit areas including the defective pixel, it is possible to detect the defective pixel using a simpler process than in a case where determining whether or not the measured value is equal to or greater than the second threshold value by generating the second image data for detection with respect to all pixels in theorganic EL panel2.
• Next, a case where the operating mode is the normal mode will be described. In the normal mode, the address of the defective pixel which is recorded in thememory11 is read out to be supplied to theimage processing unit8 by thecontrol circuit10. In the normal mode, theimage processing unit8 outputs the pixel value of each of the pixels to thepixel driving circuit9 based on the image data to be displayed. In this manner, theimage processing unit8 causes theorganic EL panel2 to display the image to be displayed. Note that, in order to prevent the current from being wastefully consumed due to the defective pixel, agradation correction circuit13 is provided in theimage processing unit8 and is configured to correct the pixel value of the defective pixel in the image data to be displayed to the pixel value for black. Then, thegradation correction circuit13 is configured to output each pixel value of the image data to be displayed in which the pixel value of the defective pixel is corrected to the pixel value for black, to thepixel driving circuit9.
• In addition, theorganic EL element7 does not emit light in the defective pixel, and thus decrease in the luminance is caused. Thus, thegradation correction circuit13 is configured to increase the pixel value of the related pixel which has a prescribed positional relationship to the defective pixel based on the pixel value of the defective pixel. Here, the related pixel means a pixel having the same color as that of the defective pixel and pixels including all pixels which are adjacent to the upper, lower, right, and left sides of the defective pixel. Then, each of the pixel values of the image data in which the pixel value of the defective pixel is corrected to the pixel value for black and the pixel value of the related pixel which is increased is output to thepixel driving circuit9. In this manner, the decrease in luminance caused by the defective pixel can be compensated for.
• Further, thegradation correction circuit13 is configured to take into account the degradation of theorganic EL element7 of the related pixel over time in correcting the pixel value of the related pixel. That is, thegradation correction circuit13 is configured to increase the pixel value of the related pixel based on not only the pixel value of the defective pixel but also a value of a monotonically increasing function K(T) with respect to elapsed time T from the time of manufacturing thedisplay device1. In this manner, the decrease of the luminance caused by the defective pixel can be reliably compensated.
• In this embodiment, threeline memories14a,14b, and14cas shown inFIG. 6 are provided in thegradation correction circuit13. Each of the line memories corresponds to one pixel line. The pixel information regarding each of the pixels in corresponding pixel lines is stored in the line memories. The pixel information includes the address and the pixel value of the pixels. Thegradation correction circuit13 reads a pixel information row stored in theline memory14aand outputs the pixel values in the read pixel information to thepixel driving circuit9 at a predetermined period. In addition, thegradation correction circuit13 updates the pixel information row stored in theline memory14aand the pixel information row stored in theline memory14bto the pixel information row stored in theline memory14band the pixel information row stored in theline memory14crespectively. And thegradation correction circuit13 updates the pixel information row stored in theline memory14cto a new pixel information row of a pixel line. Every time the pixel information row stored in theline memory14bis updated to the pixel information row stored in theline memory14c, thegradation correction circuit13 selects the pixel information in theline memory14bin order from the left and performs a process for the selected pixel information as illustrated in a flow chart ofFIG. 7. Hereinafter,FIG. 7 will be explained with the selected pixel information being denoted as target pixel information and a pixel corresponding to the target pixel information being denoted as a target pixel.
• That is, thegradation correction circuit13 determines whether or not the target pixel is the defective pixel (S101). This means that thegradation correction circuit13 determines whether or not the address of the target pixel information is the same as any address of a defective pixel. When the target pixel is a defective pixel (Y in S101), the process of thegradation correction circuit13 proceeds to step S112.
• On the other hand, when the target pixel is not a defective pixel (N in S101), thegradation correction circuit13 determines whether or not a pixel which is adjacent to the right side of the target pixel with the same color is a defective pixel (S102). In this case, since two pixels having the same color are disposed side by side every two pixels in the pixel line, thegradation correction circuit13 determines whether or not the address of the third pixel information on the right side of the target pixel information is the same as any address of a defective pixel. When the pixel which is adjacent to the right side of the target pixel with the same color is a defective pixel (Y in S102), the pixel value A of the target pixel (the pixel value of the target pixel information) is updated based on the pixel value B of the pixel which is adjacent to the right side of the target pixel with the same color (the pixel value of the third pixel information on the right side of the target pixel information) (S103). That is, thegradation correction circuit13 adds B/X to the pixel value A. Here, “X” denotes “4”. On the other hand, if the pixel which is adjacent to the right side of the target pixel with the same color is not a defective pixel (N in S102), the process of thegradation correction circuit13 proceeds to step S104 without the pixel value A being corrected.
• In step S104, thegradation correction circuit13 determines whether or not the pixel which is adjacent to the left side of the target pixel with the same color is a defective pixel (S104). In this case, thegradation correction circuit13 determines whether or not the address of the third pixel information on the left side of the target pixel information is the same as any address of a defective pixel. When the pixel which is adjacent to the left side of the target pixel with the same color is a defective pixel (Y in S104), the pixel value A of the target pixel (the pixel value of the target pixel information) is updated based on the pixel value B of the pixel which is adjacent to the left side of the target pixel with the same color (the pixel value of the third pixel information on the left side of the target pixel information) (S105). That is, thegradation correction circuit13 adds B/X to the pixel value A. On the other hand, if the pixel which is adjacent to the left side of the target pixel with the same color is not a defective pixel (N in S104), the process of thegradation correction circuit13 proceeds to step S106 without the pixel value A being corrected.
• In step S106, thegradation correction circuit13 determines whether or not the pixel which is adjacent to the lower side of the target pixel with the same color is a defective pixel (S106). In this case, thegradation correction circuit13 determines whether or not the address of the pixel information immediately below the target pixel information, stored in theline memory14c, is the same as any address of a defective pixel. When the pixel which is adjacent to the lower side of the target pixel with the same color is a defective pixel (Y in S106), the pixel value A of the target pixel (the pixel value of the target pixel information) is updated based on the pixel value B of the pixel which is adjacent to the lower side of the target pixel with the same color (the pixel value of the pixel information immediately below the target pixel information, stored in theline memory14c) (S107). That is, thegradation correction circuit13 adds B/X to the pixel value A. On the other hand, if the pixel which is adjacent to the lower side of the target pixel with the same color is not a defective pixel (N in S106), the process of thegradation correction circuit13 proceeds to step S108 without the pixel value A being corrected.
• In step S108, thegradation correction circuit13 determines whether or not the pixel which is adjacent to the upper side of the target pixel with the same color is a defective pixel (S108). In this case, thegradation correction circuit13 determines whether or not the address of the pixel information immediately above the target pixel information, stored in theline memory14a, is the same as any address of a defective pixel. When the pixel which is adjacent to the upper side of the target pixel with the same color is a defective pixel (Y in S108), the pixel value A of the target pixel (the pixel value of the target pixel information) is updated based on the pixel value B of the pixel which is adjacent to the upper side of the target pixel with the same color (the pixel value of the pixel information immediately above the target pixel information, stored in theline memory14a) (S109). That is, thegradation correction circuit13 adds B/X to the pixel value A. On the other hand, if the pixel which is adjacent to the upper side of the target pixel with the same color is not a defective pixel (N in S108), the process of thegradation correction circuit13 proceeds to step S110 without the pixel value A being corrected.
• In step S110, thegradation correction circuit13 determines whether or not at least one of the pixels which are in the vicinity of the target pixel with the same color (that is, the pixels which are adjacent to the upper, lower, right, and left sides of the target pixel with the same color) is a defective pixel (S110). When at least one of the pixels which are in the vicinity of the target pixel with the same color is a defective pixel (Y in S110), thegradation correction circuit13 reads out a value of the function K(T) stored in thememory11 to correct the pixel value A of the target pixel (the pixel value of the target pixel information) based on the value of function K(T) (S111). That is, thegradation correction circuit13 multiplies the pixel value A by the value of the function K(T). On the other hand, when a defective pixel does not exist in any of the pixels which are in the vicinity of the target pixel with the same color (N in S110), the process of thegradation correction circuit13 proceeds to step S112 without the pixel value A being corrected. In the same manner, when the target pixel is a defective pixel (Y in S101), thegradation correction circuit13 performs the step S112. When the target pixel is a defective pixel (Y in S101), the pixel value A is not corrected.
• In step S112, thegradation correction circuit13 determines whether or not the target pixel is the last pixel in the pixel line corresponding to theline memory14b(S112). That is, thegradation correction circuit13 determines whether or not the target pixel information is the pixel information stored at the rightmost side of theline memory14b. When the target pixel is not the last pixel (N in S112), the pixel information which is adjacent to the right side of the target pixel information is selected as a new target pixel information and steps after S101 are performed again. On the other hand, when the target pixel is the last pixel (Y in S112), thegradation correction circuit13 corrects the pixel value of the defective pixel stored in theline memory14ato the pixel value for black “0” (S113). That is, thegradation correction circuit13 specifies the pixel information including the same address as that of the defective pixel of the pixel information stored in theline memory14aand corrects the pixel value of the specified pixel information to the pixel value for black. The pixel value of the defective pixel is corrected to the pixel value for black through the step S113.
• FIG. 8 is a diagram illustrating a correction example of the pixel value through the process shown inFIG. 7. P denotes the pixel value of the defective pixel, Q denotes the pixel value of the pixels which are adjacent to the upper, lower, right, and left sides of the defective pixel with the same color, and R denotes the pixel values of the pixels obliquely adjacent to the defective pixel. According to the process inFIG. 7, the corrected pixel value P′ of the defective pixel is the pixel value for black “0”. The pixel value Q′ of the corrected pixels which are adjacent to the upper, lower, right, and left sides of the target pixel with the same color is “K (T)×(Q+P/X)”. That is, the pixel value P of the defective pixel before being corrected is evenly distributed and then the pixel value is multiplied by the value of the function K(T).
• As described above, the pixel value of the defective pixel is corrected to the pixel value for black in thedisplay device1. For that reason, it is possible to prevent current from being wastefully consumed due to the defective pixel.
• In addition, the pixel values of the pixels in the vicinity of the defective pixel are corrected on the basis of the pixel value of the defective pixel. Thus, it is possible to correct the decrease in luminance due to theorganic EL element7 which does not emit light in the defective pixel.
• Meanwhile, the embodiments of the invention are not limited to the above described embodiments.
• For example, thegradation correction circuit13 may correct the pixel value of the pixel which is obliquely adjacent to the defective pixel with the same color based on the pixel value of the defective pixel.FIG. 9 is a diagram illustrating a correction example of the pixel value in this case. R′ denotes the corrected pixel value of the pixel which is obliquely adjacent to the defective pixel with the same color. In this case, the pixel value P of the defective pixel before being corrected is distributed to the pixel which is obliquely adjacent to the defective pixel with the same color. Therefore, the value of “X” is changed and a distribution amount of the pixel value of the pixels which are adjacent to the upper, lower, right, and left sides of the defective pixel is reduced compared with the case ofFIG. 8. However, the distribution amount of the pixel value of the pixels which are adjacent to the upper, lower, right, and left sides of the defective pixel with the same color is assumed to be larger compared with the distribution amount of the pixel value of the pixels which are obliquely adjacent to the defective pixel with the same color.
• While there have been described what are at present considered to be certain embodiments of the invention, it will be understood that various modifications may be made thereto, and it is intended that the appended claim cover all such modifications as fall within the true spirit and scope of the invention.

Claims (7)

What is claimed is:

1. A display device comprising:

a display panel that is formed of a plurality of pixels, each of which includes a current drive type light emitting element and controls current passing through the current drive type light emitting element based on an input pixel voltage;

an image processing circuit that outputs a pixel value of each of the pixels;

a pixel voltage input circuit that inputs a pixel voltage to each of the pixels based on the pixel value of each of the pixels output from the image processing circuit; and

a defect detecting circuit that detects a defective pixel having a defect among the plurality of pixels,

wherein the image processing circuit includes

a correction circuit that corrects the pixel value of the defective pixel in image data to be displayed which is input to the image processing circuit, and then outputs each pixel value of the image data to be displayed in which the pixel value of the defective pixel is corrected, to the pixel voltage input circuit, and

wherein the correction circuit corrects the pixel value of the defective pixel to a pixel value for black.

2. The display device according toclaim 1,

wherein the current drive type light emitting element is an organic EL element, and

wherein the defective pixel is a pixel including an organic EL element in which an anode and a cathode are short-circuited.

3. The display device according toclaim 1,

wherein the correction circuit corrects a pixel value of a related pixel, of the image data to be displayed, having a prescribed positional relationship to the defective pixel based on the pixel value of the defective pixel and corrects the pixel value of the defective pixel in the image data to be displayed to the pixel value for black, and then outputs each pixel value of the image data to be displayed in which the pixel value of the defective pixel and the related pixel are corrected, to the pixel voltage input circuit.

4. The display device according toclaim 1,

wherein a plurality of unit areas are set in the display panel, and

wherein the defect detecting circuit determines, for each unit area, whether or not the unit area is a defective area including the defective pixel and then detects the defective pixel in the unit area determined as the defective area.

5. The display device according toclaim 4,

wherein the image processing circuit further includes

an image for detecting output circuit that obtains image data, the image data including the pixel value of each of the pixels for defect detection, only each of the pixel value of some of the pixels being not a pixel value for black, and then outputs each pixel value of the obtained image data to the pixel voltage input circuit,

wherein the display device further comprises

a current measuring unit that measures a total amount of the current passing through the current drive type light emitting element in the pixel of which the pixel value is not the pixel value for black,

wherein the image for detecting output circuit obtains, for each unit area, the image data for defect detection of which the pixel value only in the unit area is not the pixel value for black, and then outputs each pixel value of the obtained image data to the pixel voltage input circuit, and

wherein the defect detecting circuit determines whether or not the unit area is the defective area based on the measured value obtained from the current measuring unit in a case where all pixel values of the image data for defect detection of which the pixel pixel value only in the unit area is not the pixel value for black are output to the pixel voltage input circuit.

6. The display device according toclaim 5,

wherein the image for detecting output circuit obtains, for each of the pixels in the defective area, the image data for defect detection of which the pixel value only in the pixel is not the pixel value for black, and then outputs each pixel value of the obtained image data to the pixel voltage input circuit, and

wherein the defect detecting circuit determines whether or not the pixel in the defective area is the defective pixel based on the measured value obtained from the current measuring unit in a case where all pixel values of the image data for defect detection of which the pixel value only in the pixel is not the pixel value for black are output.

7. The display device according toclaim 3,

wherein the correction circuit corrects the pixel value of the related pixel based on the pixel value of the defective pixel and a value according to an elapsed time from reference timing.

Images